The present invention relates to the field of containers for maintaining liquid and solid materials, such as food, at a substantially constant temperature over a relatively long period of time. One highly successful device for accomplishing this objective is a Dewar flask or thermos bottle. Such a container employs a double wall filler which may be made of metal or glass and from which air is substantially evacuated.
It is known in the prior art to provide narrow mouth thermos bottles which are well situated for storing and pouring liquids and which utilize a tall and relatively small diameter vacuum filler. Wide mouth thermos bottles employ a vacuum filler of a larger diameter and have a protective liner which conforms to the internal wall of the filler. Such a thermos, while being well suited to the storing and dispensing of solid and semi-solid foods such as soups, has the disadvantage of a lower thermal insulating capability than the narrow mouth design. Further, liquids are somewhat more difficult to pour without spilling.
It is accordingly an object of the present invention to obtain the thermal insulating capability and pouring characteristics of a narrow mouth thermos while at the same time utilizing a wide mouth filler for the thermos.
It is another object of the present invention to provide a thermos which utilizes a wide mouth vacuum filler but has the pouring characteristics of a narrow mouth thermos.
It is a further object of the present invention to provide a narrow mouth thermos with a liner for preventing mixing of filler particles with food stored therein should the vacuum filler break.
It is another object of the present invention to provide a thin wall liner for converting a wide mouth vacuum filler for narrow mouth pouring.
Other objects and advantages of the present invention will become apparent from the remaining portion of the specification.